Java 将数据导出到（自定义格式）文本文件

发布于 2024-12-28 21:32:55 字数 4383 浏览 3 评论 0原文

我被要求从事这项后端计划工作，将一些客户数据（从电子商务数据库）导出到自定义格式的文本文件。下面的代码是我发现的。

我只是想把它全部删除，但我做不到。我是否可以在不改变太多的情况下改进它？

public class AConverter implements CustomerConverter {

    protected final Logger LOG = LoggerFactory.getLogger(AConverter.class);

    private final static String SEPARATOR = ";";
    private final static String CR = "\n";

    public String create(Customer customer) {

        if (customer == null)
            return null;

        LOG.info("Exporting customer, uidpk: {}, userid: {}", customer.getUidPk(), customer.getUserId());

        StringBuilder buf = new StringBuilder();

        buf.append("<HEAD>");
        buf.append(SEPARATOR);
        buf.append(String.valueOf(customer.getUidPk()));
        buf.append(SEPARATOR);
        byte[] fullName = null;
        try {
            fullName = customer.getFullName().getBytes("UTF-8");
        } catch (UnsupportedEncodingException e1) {
            fullName = customer.getFullName().getBytes();
        }
        String name = null;
        try {
            name = new String(fullName, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            name = customer.getFullName();
        }
        buf.append(limitString(name, 40));
        buf.append(SEPARATOR);
        final CustomerAddress preferredShippingAddress = customer.getPreferredShippingAddress();
        if (preferredShippingAddress != null) {
            final String street1 = preferredShippingAddress.getStreet1();
            if (street1 != null) {
                buf.append(limitString(street1, 40));
            }
        } else {
            buf.append(" ");
        }
        buf.append(SEPARATOR);

        final String addressStr = buildAddressString(customer);
        buf.append(limitString(addressStr, 40));
        buf.append(SEPARATOR);
        buf.append(limitString(customer.getEmail(), 80));
        buf.append(SEPARATOR);
        if (preferredShippingAddress!=null && preferredShippingAddress.getStreet2() != null) {
            buf.append(limitString(preferredShippingAddress.getStreet2(), 40));
        } else {
            buf.append(" ");
        }
        buf.append(SEPARATOR);
        buf.append(limitString(customer.getPhoneNumber(), 25));
        buf.append(SEPARATOR);
        if (preferredShippingAddress!=null) {
            if(preferredShippingAddress.getCountry()!=null) {
                buf.append(preferredShippingAddress.getCountry());
            } else {
                buf.append(" ");
            }
        } else {
            buf.append(" ");
        }
        buf.append(SEPARATOR);
        if (preferredShippingAddress!=null) {
            if(preferredShippingAddress.getCountry()!=null) {
                buf.append(preferredShippingAddress.getCountry());
            } else {
                buf.append(" ");
            }
        } else {
            buf.append(" ");
        }
        buf.append(SEPARATOR);

        String fodselsnummer = " ";
        try {
            Map<String, AttributeValue> profileValueMap = customer.getProfileValueMap();
            AttributeValue attributeValue = profileValueMap.get("CODE");
            fodselsnummer = attributeValue.getStringValue();
        } catch (Exception e) {
        }
        buf.append(fodselsnummer);
        buf.append(CR);
        final String string = buf.toString();

        return string;

    }

    private String buildAddressString(Customer customer) {
        final CustomerAddress preferredShippingAddress = customer.getPreferredShippingAddress();
        if (preferredShippingAddress != null) {
            final String zipOrPostalCode = preferredShippingAddress.getZipOrPostalCode();
            final String city = preferredShippingAddress.getCity();
            if (zipOrPostalCode != null && city != null) {
                return zipOrPostalCode + " " + city;
            } else if(zipOrPostalCode == null && city != null) {
                return city;
            } else if(zipOrPostalCode != null && city == null) {
                return zipOrPostalCode;
            }
        }
        return " ";
    }

    private String limitString(String value, int numOfChars) {
        if (value != null && value.length() > numOfChars)
            return value.substring(0, numOfChars);
        else
            return value;
    }

}

原文

I was asked to work on this back-end scheduled job that export some customers data (from an e-commerce DB) to a custom-format text file. The code that follows is what I found.

I just would like to delete it all, but I can't. Would it be possible for me to improve this without changing it so much?

public class AConverter implements CustomerConverter {

    protected final Logger LOG = LoggerFactory.getLogger(AConverter.class);

    private final static String SEPARATOR = ";";
    private final static String CR = "\n";

    public String create(Customer customer) {

        if (customer == null)
            return null;

        LOG.info("Exporting customer, uidpk: {}, userid: {}", customer.getUidPk(), customer.getUserId());

        StringBuilder buf = new StringBuilder();

        buf.append("<HEAD>");
        buf.append(SEPARATOR);
        buf.append(String.valueOf(customer.getUidPk()));
        buf.append(SEPARATOR);
        byte[] fullName = null;
        try {
            fullName = customer.getFullName().getBytes("UTF-8");
        } catch (UnsupportedEncodingException e1) {
            fullName = customer.getFullName().getBytes();
        }
        String name = null;
        try {
            name = new String(fullName, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            name = customer.getFullName();
        }
        buf.append(limitString(name, 40));
        buf.append(SEPARATOR);
        final CustomerAddress preferredShippingAddress = customer.getPreferredShippingAddress();
        if (preferredShippingAddress != null) {
            final String street1 = preferredShippingAddress.getStreet1();
            if (street1 != null) {
                buf.append(limitString(street1, 40));
            }
        } else {
            buf.append(" ");
        }
        buf.append(SEPARATOR);

        final String addressStr = buildAddressString(customer);
        buf.append(limitString(addressStr, 40));
        buf.append(SEPARATOR);
        buf.append(limitString(customer.getEmail(), 80));
        buf.append(SEPARATOR);
        if (preferredShippingAddress!=null && preferredShippingAddress.getStreet2() != null) {
            buf.append(limitString(preferredShippingAddress.getStreet2(), 40));
        } else {
            buf.append(" ");
        }
        buf.append(SEPARATOR);
        buf.append(limitString(customer.getPhoneNumber(), 25));
        buf.append(SEPARATOR);
        if (preferredShippingAddress!=null) {
            if(preferredShippingAddress.getCountry()!=null) {
                buf.append(preferredShippingAddress.getCountry());
            } else {
                buf.append(" ");
            }
        } else {
            buf.append(" ");
        }
        buf.append(SEPARATOR);
        if (preferredShippingAddress!=null) {
            if(preferredShippingAddress.getCountry()!=null) {
                buf.append(preferredShippingAddress.getCountry());
            } else {
                buf.append(" ");
            }
        } else {
            buf.append(" ");
        }
        buf.append(SEPARATOR);

        String fodselsnummer = " ";
        try {
            Map<String, AttributeValue> profileValueMap = customer.getProfileValueMap();
            AttributeValue attributeValue = profileValueMap.get("CODE");
            fodselsnummer = attributeValue.getStringValue();
        } catch (Exception e) {
        }
        buf.append(fodselsnummer);
        buf.append(CR);
        final String string = buf.toString();

        return string;

    }

    private String buildAddressString(Customer customer) {
        final CustomerAddress preferredShippingAddress = customer.getPreferredShippingAddress();
        if (preferredShippingAddress != null) {
            final String zipOrPostalCode = preferredShippingAddress.getZipOrPostalCode();
            final String city = preferredShippingAddress.getCity();
            if (zipOrPostalCode != null && city != null) {
                return zipOrPostalCode + " " + city;
            } else if(zipOrPostalCode == null && city != null) {
                return city;
            } else if(zipOrPostalCode != null && city == null) {
                return zipOrPostalCode;
            }
        }
        return " ";
    }

    private String limitString(String value, int numOfChars) {
        if (value != null && value.length() > numOfChars)
            return value.substring(0, numOfChars);
        else
            return value;
    }

}

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飘过的浮云 2025-01-04 21:32:55

你说你想改进它，你想删除它，但你不能。我不知道为什么你不能。我也不明白你为什么要删除它。但在我看来，这就像我在阅读 Martin Fowler 的重构之前所持的态度。如果你还没有读过那本书，我强烈建议你读一读。

当然可以改进这段代码（或任何代码）而无需全部重写。最明显的改进是通过创建一些实用方法来消除 create 方法中的一些重复代码，然后将 create 方法分解为几个较小的方法。模板方法。

此外，create 方法中存在一段可疑的代码，该代码将客户的姓名转换为 UTF-8 字节流，然后再转换回字符串。我无法想象那是做什么用的。最后，如果客户为 null，则返回 null。这不太可能是必要的或明智的。

为了好玩，我决定对这段代码进行一些重构。（请注意，正确的重构涉及单元测试；我没有对此代码进行任何测试，甚至没有编译下面的代码，更不用说对其进行测试了。）这是您可以重写此代码的一种可能的方法：

public class AConverter implements CustomerConverter {
    protected final Logger LOG = LoggerFactory.getLogger(AConverter.class);

    private final static String SEPARATOR = ";";
    private final static String CR = "\n";

    public String create(Customer customer) {
        if (customer == null) throw new IllegalArgumentException("no cust");

        LOG.info("Exporting customer, uidpk: {}, userid: {}",
                customer.getUidPk(), customer.getUserId());

        StringBuilder buf = new StringBuilder();
        doHead(buf, customer);
        doAddress(buf, customer);
        doTail(buf, customer);
        return buf.toString();
    }

    private void doHead(StringBuilder buf, Customer customer) {
        append(buf, "<HEAD>");
        append(buf, String.valueOf(customer.getUidPk()));
        append(buf, limitTo(40, customer.getFullName()));
    }

    private void doAddress(StringBuilder buf, Customer customer) {
        append(buf, limitTo(40, street1of(customer)));
        append(buf, limitTo(40, addressOf(customer)));
        append(buf, limitTo(80, customer.getEmail()));
        append(buf, limitTo(40, street2of(customer)));
        append(buf, limitTo(25, customer.getPhoneNumber()));
        append(buf, countryOf(customer));
        append(buf, countryOf(customer));
    }

    private void doTail(StringBuilder buf, Customer customer) {
        buf.append(fodselsnummerOf(customer));
        buf.append(CR);
    }

    private void append(StringBuilder buf, String s) {
        buf.append(s).append(SEPARATOR);
    }

    private String street1of(Customer customer) {
        final CustomerAddress shipto = customer.getPreferredShippingAddress();
        if (shipto == null) return " ";
        if (shipto.getStreet1() != null) return shipto.getStreet1();
        return " ";
    }

    private String street2of(Customer customer) {
        final CustomerAddress shipto = customer.getPreferredShippingAddress();
        if (shipto == null) return " ";
        if (shipto.getStreet2() != null) return shipto.getStreet2();
        return " ";
    }

    private String addressOf(Customer customer) {
        final CustomerAddress shipto = customer.getPreferredShippingAddress();
        if (shipto == null) return " ";

        final String post = preferredShippingAddress.getZipOrPostalCode();
        final String city = preferredShippingAddress.getCity();

        if (post != null && city != null) return post + " " + city;
        if (post == null && city != null) return city;
        if (post != null && city == null) return post;
        return " ";
    }

    private String countryOf(Customer customer) {
        final CustomerAddress shipto = customer.getPreferredShippingAddress();
        if (shipto == null) return " ";
        if (shipto.getCountry() != null) return shipto.getCountry();
        return " ";
    }

    private String limitTo(int numOfChars, String value) {
        if (value != null && value.length() > numOfChars)
            return value.substring(0, numOfChars);
        return value;
    }

    private String fodelsnummerOf(Customer customer) {
        try {
            Map<String, AttributeValue> profileValueMap =
                customer.getProfileValueMap();
            AttributeValue attributeValue = profileValueMap.get("CODE");
            return attributeValue.getStringValue();
        } catch (Exception e) {
            return " ";
        }
    }
}

我还注意到有如果客户数据的任何字段（例如电子邮件地址）中碰巧有分号，则说明自定义格式文本文件的格式有问题，因为那是分隔符。我相信这是一个已知问题？

You say you want to improve it, you'd like to delete it, but you can't. I'm not sure why you can't. I also don't understand why you'd want to delete it. But it sounds to me like the kind of attitude I used to have before I read Refactoring by Martin Fowler. I would strongly suggest you read that book, if you haven't already.

It is certainly possible to improve this code (or any code) without rewriting it all. The most obvious improvements would be to eliminate some of the repetitive code in the create method by creating some utility methods, and then breaking up the create method into several smaller methods à la template methods.

Also, there is a questionable bit of code in the create method that turns the customer's name into a UTF-8 byte stream and then back into a string. I can't imagine what that's for. Finally, it returns null if the customer is null. That is unlikely to be necessary or wise.

For fun, I decided to do a little refactoring on this code. (Note that proper refactoring involves unit tests; I don't have any tests for this code and have not even compiled the code below, much less tested it.) Here is one possible way you could rewrite this code:

public class AConverter implements CustomerConverter {
    protected final Logger LOG = LoggerFactory.getLogger(AConverter.class);

    private final static String SEPARATOR = ";";
    private final static String CR = "\n";

    public String create(Customer customer) {
        if (customer == null) throw new IllegalArgumentException("no cust");

        LOG.info("Exporting customer, uidpk: {}, userid: {}",
                customer.getUidPk(), customer.getUserId());

        StringBuilder buf = new StringBuilder();
        doHead(buf, customer);
        doAddress(buf, customer);
        doTail(buf, customer);
        return buf.toString();
    }

    private void doHead(StringBuilder buf, Customer customer) {
        append(buf, "<HEAD>");
        append(buf, String.valueOf(customer.getUidPk()));
        append(buf, limitTo(40, customer.getFullName()));
    }

    private void doAddress(StringBuilder buf, Customer customer) {
        append(buf, limitTo(40, street1of(customer)));
        append(buf, limitTo(40, addressOf(customer)));
        append(buf, limitTo(80, customer.getEmail()));
        append(buf, limitTo(40, street2of(customer)));
        append(buf, limitTo(25, customer.getPhoneNumber()));
        append(buf, countryOf(customer));
        append(buf, countryOf(customer));
    }

    private void doTail(StringBuilder buf, Customer customer) {
        buf.append(fodselsnummerOf(customer));
        buf.append(CR);
    }

    private void append(StringBuilder buf, String s) {
        buf.append(s).append(SEPARATOR);
    }

    private String street1of(Customer customer) {
        final CustomerAddress shipto = customer.getPreferredShippingAddress();
        if (shipto == null) return " ";
        if (shipto.getStreet1() != null) return shipto.getStreet1();
        return " ";
    }

    private String street2of(Customer customer) {
        final CustomerAddress shipto = customer.getPreferredShippingAddress();
        if (shipto == null) return " ";
        if (shipto.getStreet2() != null) return shipto.getStreet2();
        return " ";
    }

    private String addressOf(Customer customer) {
        final CustomerAddress shipto = customer.getPreferredShippingAddress();
        if (shipto == null) return " ";

        final String post = preferredShippingAddress.getZipOrPostalCode();
        final String city = preferredShippingAddress.getCity();

        if (post != null && city != null) return post + " " + city;
        if (post == null && city != null) return city;
        if (post != null && city == null) return post;
        return " ";
    }

    private String countryOf(Customer customer) {
        final CustomerAddress shipto = customer.getPreferredShippingAddress();
        if (shipto == null) return " ";
        if (shipto.getCountry() != null) return shipto.getCountry();
        return " ";
    }

    private String limitTo(int numOfChars, String value) {
        if (value != null && value.length() > numOfChars)
            return value.substring(0, numOfChars);
        return value;
    }

    private String fodelsnummerOf(Customer customer) {
        try {
            Map<String, AttributeValue> profileValueMap =
                customer.getProfileValueMap();
            AttributeValue attributeValue = profileValueMap.get("CODE");
            return attributeValue.getStringValue();
        } catch (Exception e) {
            return " ";
        }
    }
}

I also notice that there is a problem with your format for the custom-format text file if any of the fields of the customer data (email address, for example) happen to have a semicolon in them, because that is your separator character. I trust that is a known issue?

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